Auto-Transitional Local Angle Domain Illumination Compensated Multiscale Full Waveform Inversion

For deep reservoir exploration, precise inversion of the deep target is important. However, the resolution of full waveform inversion (FWI) in the deeper region may not be as fine as in the shallow region due to the acquisition geometry and complex local structure. Besides, the cycle-skipping problem is critical and significantly influences the accuracy of the inversion in FWI. In order to increase the resolution for the deep region and reduce the cycle-skipping problem, we propose a local angle domain-based inversion method. We decompose the incident and scattered wavefields around a local target into the local angle domain. Then, by the simultaneous construction of the local angle filter and the local resolution function based on the wavefield decomposition, a local angle domain multiscale inversion method with illumination compensation is conducted. Based on the convergence criterion, we construct an auto-transitional misfit function that can avoid manual intervention for the multiscale inversion process. Numerical tests proved the feasibility of the proposed strategy.